The Spanish word 'besito' meaning 'little kiss' comes from combining the Spanish word 'beso' (kiss) with the diminutive suffix '-ito'. The word 'beso' itself derives from the Latin word 'basium', which also meant 'kiss'. The diminutive suffix '-ito' is a very common and productive suffix in Spanish that adds the meaning of smallness, endearment, or affection to the base word.

The most obvious related Spanish word is 'beso' (kiss), which is the base word from which 'besito' is formed. Other related words include the verb 'besar' (to kiss) and other diminutive forms like 'besicos' (little kisses, used in some regions). Understanding that 'besito' is simply 'beso' + '-ito' helps learners recognize how diminutives work in Spanish.

While English doesn't have any common words directly related to 'besito' or 'basium', the word 'buss' (meaning to kiss) is believed by some etymologists to be distantly related to the Latin 'basium', though this connection is debated. The lack of related English words reflects how English and Spanish drew from different sources for their vocabulary related to kissing - English primarily used Germanic roots while Spanish maintained the Latin terminology.